As a background technique in the present technical field, Japanese Patent No. 5122810 (Patent Document 1) is cited. This publication document describes an edge termination structure for a silicon carbide device, and this edge termination structure has a plurality of concentric-circle floating guard rings in a silicon carbide layer, which are arranged so as to be separated from a silicon-carbide-based semiconductor junction.
In addition, the Extended Abstract of the 73rd academic lecture presentation of the Japan Society of Applied Physics (Non-Patent Document 1) describes a JTE (Junction Termination Extension: a junction termination portion, a junction termination extension portion, or an edge termination portion) structure obtained by combining a two-zone JTE and a space modulation type JTE.